Many light trucks have tailgates that can open to extend the bed and permit loading and unloading, and close to create a confined area. Typically, the range of motion of the tailgate is through about 90 degrees from the opened to the closed positions, with the inner surface of the tailgate being roughly aligned with the bed in the open position.
As technologies improve and proliferate, drivers of passenger cars and light trucks expect more automation and convenience, with automatic opening of the tailgate becoming a standard feature. However, power actuation is not always desired, as drivers may wish to operate the tailgate manually as well. Although complex systems involving a plurality of sensors and computer components could be developed, consumers prefer to have these features without the burden of excessive cost.
It has been a challenge to develop a mechanism for opening and shutting a tailgate which can be operated in a powered mode or by manual effort, and which is capable of tracking the position of the tailgate regardless of the mode in which the device is operated, and to do so with cost-effective components. Moreover, design requirements and constraints for this application include high torque loads necessary to move a tailgate between the positions while providing the desired manual actuation override and safety provisions.